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Short Summary
Main recommendation: Use Li-Fi (Light Fidelity), which transmits data through subtle brightness changes in off-the-shelf LED lights, and use existing solar cells as receivers instead of Wi-Fi or dedicated photodetectors. Harald Haas argues this can extend internet access and connect billions of Internet of Things devices while staying nearly energy neutral by reusing existing infrastructure. He presents a lab prototype and says his team expects to bring it to market within two to three years.
Key Points
- Li-Fi encodes data in fast brightness fluctuations of LEDs that the human eye cannot see, and the speaker says it is fast and secure.
- A solar cell that normally harvests energy also receives the data, because the energy it harvests fluctuates with the light's brightness changes.
- In the lab, the speaker says a standard off-the-shelf solar cell received up to 50 megabits per second, which he describes as faster than most broadband connections today.
- The demonstration showed that blocking the solar cell stopped both energy harvesting and the video stream, confirming the solar cell acts as the receiver.
- A handkerchief placed over the solar cell, simulating fog, reduced harvested energy but the high-definition video kept streaming, because enough light still passed through.
- The speaker suggests this could work with existing solar cells on huts, translucent windows, street furniture, and Internet of Things devices that would otherwise need frequent charging or battery replacement.
Details Worth Noting
- Concrete instructions: The transcript gives no step-by-step setup or buyer instructions for viewers. The demonstrated setup was an off-the-shelf LED lamp streaming video, a standard off-the-shelf solar cell connected to a laptop, and an instrument visualizing harvested energy. Practical use described was pairing a laser or LED transmitter on a hill or lamppost with an existing solar cell on a roof.
- The speaker first demonstrated this publicly at TED in 2011; this is described as the first public demonstration of video transmission from an LED to a solar cell with a laptop as receiver.
- Data speed of 50 Mbps is described as a lab result, not a field measurement.
- The solar cell's receiving function is described as additional to its primary energy-harvesting role, so it does not require a separate photodetector.
- The prototype is described as lab-only; the speaker expects market availability in two to three years but gives no certainty.
Bottom Line
Li-Fi using existing LEDs and solar cells is presented as a low-energy way to extend internet access and connect large numbers of devices, though the speaker frames it as a prototype still in the lab.